Canine Spine Anatomy

A dog's spine is similar to a human's spine. It's a collection of bones called vertebrae and is designed to support weight and protect the spinal cord inside. The spinal cord is made of cable-like nerves used to transmit information from the brain to the rest of the body and vice versa. The spinal cord is covered with fibrous membranes running the length of the spine.

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However, a horizontal alignment gives the canine spine — which extends from the base of the head to the end of the tail — some advantages over a human spine. For instance, there are fewer compression issues because weight is more evenly distributed across vertebrae positioned side by side rather than stacked one above the other.

Dog spine anatomy is similar to human spine anatomy. Located on the dorsal side, or top, of the dog's body, a canine spine is divided into four main regions, including the neck, called cervical; the mid-back area, called thoracic; the lower back, or lumbar; and the pelvic spine, also called the sacral. Many of the injuries that happen to a human spine can happen to a canine spine. However, dogs are more stoic when it comes to pain, so injury can be harder to pinpoint.

In total, there are 30 vertebrae in a dog spine: seven in the neck, 13 in the thoracic, seven in the lumbar, and three in the pelvic area. Dogs have more vertebrae than humans, including an extra one that forms the tail. Small joints between vertebrae allow for movement and are held together by ligaments and muscles.

Intervertebral discs are a type of spongy cartilage located between vertebrae. Dogs have 28 intervertebral discs — one between each vertebra — in their spine, enabling the vertebrae to move by cushioning movement and absorbing shock and vibration.

Like people, dogs can experience a slipped disc in the spine, also called intervertebral disc herniation. The intervertebral disc is a cushion between the vertebrae offering a padding between the bones in the spine. When this disc moves out of place, it can put pressure on the spinal cord, causing pain and damage to the nerves. Bleeding can create additional pressure.

Signs of a slipped or herniated disc in a dog include loss of coordination, weakness or lameness in the back end that is often mistaken for leg or knee injury, incontinence, paralysis, crying, reaction to touch, and personality changes. A low head and rounding of the back are common clues to spinal issues. A CT scan or MRI might be necessary to determine the extent of the compression, and clearly, veterinary attention is required because spinal injuries are serious.

A dog's lumbar area is located in the lower spine and is composed of seven vertebrae protecting the spinal column. What's interesting is at this point, the canine spinal cord changes shape from a tubelike structure to a collection of nerves that have a curved, tapered shape, commonly referred to as a "horse's tail." The lumbar connects to the pelvic spine, called sacral.

It's also in the lumbar and sacral region where a dog most likely experiences a sore back, sometimes debilitating. Lumbosacral syndrome occurs here, and it's a narrowing of the spinal canal, causing nerve compression. This narrowing has a number of potential causes, including arthritis, infections, herniation of the cartilage between the discs, or a spinal tumor.

Whatever the cause, pressure and pain is the result, and the dog requires medical attention. Symptoms range from difficulty walking to extreme reaction to touch to complete paralysis. Understanding dog spine anatomy can help you recognize dog spine problems.